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What Is an Antithyroglobulin Antibody Test?

Medically Reviewed by Dan Brennan, MD on June 18, 2021

‌Your thyroid is a small butterfly-shaped organ in the front of your neck. It has a lot of important roles, including making hormones that control your metabolism and help your body grow and develop. The thyroid makes a protein called thyroglobulin that helps make thyroid hormones thyroxine (T4) and triiodothyronine (T3).

Your Thyroid and Immune System Antibodies

‌Your immune system is a group of glands, cells, and organs that work together to keep your body safe from invading threats. White blood cells and lymph nodes are part of this system, but so are your tonsils, spleen, bone marrow, gastrointestinal tract, and skin. Threats are most often foreign matter like bacteria, viruses, chemicals, parasites, and other unwanted organisms. 

The immune system makes antibodies, which are proteins that bind to the proteins in foreign invaders. Your immune system can sometimes think a part of your body is foreign, and that’s when damage may occur.‌

Autoimmune disorders can affect many parts of the body, including the thyroid. An autoimmune condition is when your immune system attacks the proteins in your own body cells, even though they are not harmful or foreign. 

When your immune system thinks your thryoglobulin proteins are foreign, it sends out antibodies to get rid of the threat. If you have a thyroid autoimmune disorder, or if your doctor thinks you have an issue with your thyroid, they will order a test known as an antithyroglobulin antibody test. 

What Is the Antithyroglobulin Antibody Test?

‌‌Also called thyroid antibody test or thyroglobulin antibody test, this blood test checks your blood for thyroglobulin antibodies. Up to 10 percent of the U.S. population may have small amounts of this antibody in their blood all the time. Having a lot of these antibodies in your blood means your thyroid isn’t working like it should. ‌‌

You could also have higher or lower amounts of thyroid hormones. In healthy thyroids, most adults have anywhere from 5 to 11 micrograms per deciliter of T4 thyroxine and 0.1 to 0.2 micrograms per deciliter of T3 triiodothyronine.‌‌

If your doctor has diagnosed you with a thyroid condition or a thyroid autoimmune disorder, you likely have a lot more of the antithyroglobulin antibody in your blood. ‌‌

You may have antithyroglobulin antibodies in your blood if you have:

  • ‌‌Hypothyroidism. Your body doesn’t make or release enough thyroid hormone for your metabolic rate.
  • Hyperthyroidism. Your body releases too much thyroid hormone into your bloodstream.
  • Goiter. When you have a goiter, your thyroid gland is inflamed or doesn’t have enough iodine available for hormone production. ‌

‌Having antithyroglobulin antibodies can mean you have an autoimmune disorder like lupus, Grave’s disease, or Hashimoto’s thyroiditis — also called Hashimoto’s disease. It could also mean you have Type 1 diabetes, thyroiditis, thyroid cancer or thyroid nodules.  

What Are the Signs and Symptoms of Thryoglobulin and Thyroid Hormone Issues?

‌‌You may have an issue with your thyroid if you have some of the following symptoms:

  • ‌Anxiety or nervousness
  • ‌Trouble sleeping
  • ‌Chronic fatigue
  • ‌Sensitivity to heat or cold
  • ‌Forgetfulness
  • ‌Poor concentration
  • ‌Weight gain or weight loss
  • ‌Muscle weakness or tremors
  • ‌Dry hair
  • ‌Hoarse voice
  • ‌Vision problems, including eye irritation
  • ‌Frequent, heavy menstrual periods

What to Expect With the Antithyroglobulin Antibody Test

‌‌When you arrive for your antithyroglobulin antibody test, a nurse or lab technician will have you sit comfortably in a chair. They will gather a few supplies to take a blood sample from your vein. ‌‌

First, they will put an elastic band around your upper arm to increase the pressure and help the veins in your lower arm pop out. Then they will sterilize the area and insert a small needle called a butterfly needle into your vein. This needle is attached to a syringe or test tube vial, so they can draw enough blood for the antithyroglobulin antibody test. ‌

‌Once the healthcare professional is finished, they undo the elastic band, remove the needle, and apply pressure to the wound to stop the bleeding. They’ll cover the needle mark with a bandage and finish marking the blood sample with your identification. 

The nurse sends the blood to the lab, either an on-site or off-site lab, for testing. Your doctor will get the results as soon as they are ready. 

Next Steps

‌‌Once your doctor reviews the blood test results, they’ll contact you to talk about what the numbers mean. If your results showed minimal or no antithyroglobulin antibodies, you are not likely to have a serious autoimmune disorder or other thyroid issue. ‌‌

If your test results come back showing you have a high amount of antithyroglobulin antibodies, your doctor will likely want you to get further testing. They may order blood tests for specific conditions or other general tests to help identify your health condition. Once you know your health condition, you can begin treatment to help you feel better.

WebMD Medical Reference

Sources

SOURCES

Alberts, B., Johnson, A., Lewis, J. et al. Molecular Biology of the Cell. 4th edition, Garland Science, 2002. “B Cells and Antibodies.” 

American Thyroid Association: “Thyroid Function Tests.” 

British Thyroid Foundation: “Your thyroid gland.” 

Cleveland Clinic: "Immune System," “Thyroid Disease.”

‌KidsHealth from Nemours: “Blood Test: Thyroglobulin Antibodies (TgAb).” 

Merck Manual: “Autoimmune Disorders.” 

The Journal of the American Medical Association: “Thyroglobulin for Monitoring for Thyroid Cancer Recurrence.”

University of Rochester Medical Center: “Thyroid Antithyroglobulin Antibody.” 

World Journal of Biological Chemistry: “Use of thyroglobulin as a tumour marker.” 

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